Supplemental Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 3,344	$ 3,122	$ 2,798	$ 2,518	$ 3,110	$ 3,588	$ 2,125	$ 2,342	$ 11,782	$ 11,165	$ 9,297
Gross (loss) profit	(3,317)	986	1,053	897	1,149	1,301	954	1,055	(381)	4,459	4,400
Loss from operations	(19,411)	(14,532)	(17,590)	(20,027)	(15,080)	(15,165)	(15,725)	(17,730)	(71,560)	(63,700)	(72,831)
Net loss	$ (22,803)	$ (8,986)	$ (21,674)	$ (24,239)	$ (18,912)	$ (18,757)	$ (19,230)	$ (21,309)	$ (77,702)	$ (78,208)	$ (84,305)
Basic net loss per share (dollars per share)	$ (0.34)	$ (0.15)	$ (0.36)	$ (0.41)	$ (0.33)	$ (0.33)	$ (0.35)	$ (0.39)	$ (1.26)	$ (1.40)	$ (1.55)
Diluted net loss per share (dollars per share)	$ (0.34)	$ (0.15)	$ (0.36)	$ (0.41)	$ (0.33)	$ (0.33)	$ (0.35)	$ (0.39)	$ (1.26)	$ (1.40)	$ (1.55)